Helichrysum stoechas (L.) Moench Inflorescence Extract for Tomato Disease Management

Abstract

Helichrysum stoechas is a singular halophyte that has been shown to have anti-inflammatory, antioxidant, and allelopathic properties. In the work presented herein, we have characterized its inflorescences hydromethanolic extract and assessed its antifungal activity for the pre- and postharvest management of tomato crop diseases. Gas chromatography–mass spectrometry characterization of the extract showed that 4-ethenyl-1,3-benzenediol, 2,3-dihydro-benzofuran, quinic acid, 3,5-dihydroxy-6,7,8-trimethoxy-2-phenyl-4H-1-benzopyran-4-one, 1,6-anhydro-β-D-glucopyranose, catechol, scopoletin, and maltol were the main constituents. The co-occurrence of pyranones, benzenediols, and quinic acids as phytoconstituents of H. stoechas extract resulted in promising in vitro minimum inhibitory concentrations of 500, 375, 500, 187.5, 187.5, and 375 μg·mL−1 against mycelia of Alternaria alternata, Colletotrichum coccodes, Fusarium oxysporum f. sp. lycopersici, Rhizoctonia solani, Sclerotinia sclerotiorum, and Verticillium dahliae, respectively. Further, to assess the potential of H. stoechas inflorescence extract for postharvest tomato crop protection, ex situ tests were conducted against C. coccodes, obtaining high protection at a dose of 750 μg·mL−1. Taking into consideration that the demonstrated activity is among the highest reported to date for plant extracts and comparable to that of the synthetic fungicides tested as positive controls, H. stoechas inflorescence extract may be put forward as a promising biorational and may deserve further testing in field-scale studies.

Carvacrol Encapsulation in Chitosan–Carboxymethylcellulose–Alginate Nanocarriers for Postharvest Tomato Protection

“…Fungal conidial suspensions were prepared following the procedures outlined in [65,66]. Conidia were harvested from 1-week-old PDB cultures of B. cinerea and C. coccodes, as well as from a 2-week-old PDB culture of P. expansum.…”

“…The efficacy of COS-CMC-ALG NCs loaded with carvacrol for postharvest protection of tomato fruits (cv. 'Daniela'), cultivated under EU organic farming regulations at Huerta El Gurullo (Cuevas del Almanzora, Almería, Spain), was assessed as outlined in [65,66]. All tested fruits, exhibiting uniform dimensions (approximately 75 mm in diameter), displayed no apparent signs of disease.…”

Uncaria tomentosa-Loaded Chitosan Oligomers–Hydroxyapatite–Carbon Nitride Nanocarriers for Postharvest Fruit Protection

“…The efficacy of COS-HAp-g-C 3 N 4 -BNP treatment in postharvest protection of other fruits, namely, mango, peach, apple, and kiwifruit, artificially infected with C. gloeosporioides, M. laxa, P. expansum, and S. sclerotiorum, respectively, was also evaluated under controlled laboratory conditions, following the procedure indicated in [33]. The surface disinfection procedure and experiment design (involving four groups of 24 fruits each, i.e., three replicates with 8 fruits per replicate and treatment) were similar to those described above for strawberries, with one group treated with COS-HAp-g-C 3 N 4 -BNP NCs at a concentration equal to the MIC determined in vitro (375, 250, 375, and 187.5 µg•mL −1 , respectively), another group treated at twice the MIC (750, 500, 750, and 375 µg•mL −1 , respectively), and negative and positive controls.…”